Ten years later, the Day of Disaster was sent into motion when Dr. Eggman conducted a series of kidnappings of Elise to get a hold of Iblis. The Day of Disaster itself took place two days after the Festival of the Sun when Elise died while aboard the Egg Carrier when it crashed from malfunctioning engines, releasing Iblis into the world. Now free, Iblis was able to ravage world with his flames, creating the world of burning ruins and unstable crusts that Silver would be born into.
Approximately two hundred years after the Day of Disaster, Mephiles the Dark tricked the peace-seeking Silver into thinking that Sonic the Hedgehog was responsible for the Day of Disaster for a plot to ensure Iblis' release. Silver thus sought to retroactively prevent the Day of Disaster from occurring by killing Sonic in the past. In the end though, he and Sonic worked together to prevent the Day of Disaster by sending Sonic back in time to save Elise before she died.
After the paradox created by Sonic and Elise, history was rewritten so that Iblis was never split from Solaris, thereby eliminating the Day of Disaster from existence.
↑ 2.02.1Sonic Team (14 November 2006) Sonic the Hedgehog (2006). PlayStation 3. Sega. Area/Level: Last Story. "Dr. Eggman: Iblis' seal has been broken. Due to Mephiles' manipulation. / ... / Dr. Eggman: Mephiles played us all for fools! His plan all along was to cause the princess to be so consumed with despair that she'd cry."
↑Sonic Team (14 November 2006) Sonic the Hedgehog (2006). PlayStation 3. Sega. Crisis City (Sonic's Episode). "Miles "Tails" Prower: According to the data, the princess died when she was kidnapped by Eggman! Apparently, Eggman's battle ship exploded! The date of this incident was... two days after the Festival of the Sun!"
↑Sonic Team (November 14 2006) Sonic the Hedgehog (2006). PlayStation 3. Sega. Crisis City (Silver's Episode). "Mephiles the Dark: To fix this present timeline, you need to change the past. ... In order to change the past, you must eliminate the individual who has awakened Iblis. The Iblis Trigger."